At Least 3 Bodies Of Intelligence Research: Psychometric, Physiological and Social
[I]ntelligence is currently defined, assessed, and studied on at least three different levels: psychometric, psychological, and social (Eysenck, 1988; Flynn 2007). Each level has its own organizing concepts, hypotheses, research methodologies, and conclusions that can limit comparison and consensus. For example, the physiologial approach typically employs advanced technology to examine indices of intelligence in the brain, whereas the social (or societal usefulness) approach uses performance on "real-world" tasks to study intellectual skills in context. Fortunately, there has been some recent cross-fertilization between levels, which bodes well for future agreement on what it means to be intelligent (Flynn, 2007).
Eysenck, H. J. (1998). The concept of "intelligence": Useful or useless? Intelligence, 12, 1-16.
Flynn, J. R. (2007). What is intelligence? Beyond the Flynn effect. New York, NY: Cambridge University Press.
-- Janet E. Davidson , Iris A. Kemp
from "The Cambridge Handbook of Intelligence"
Quoted on Fri Nov 2nd, 2012